The present invention relates to a manufacturing method of semiconductor wafer having a lid part on each of a plurality of semiconductor elements formed in the semiconductor wafer, and a manufacturing method of semiconductor device using this manufacturing method of semiconductor wafer.
Solid-state image pickup devices, such as CCDs and CMOS imagers, that are one kind of semiconductor devices have been practically used in a variety of fields. A solid-state image pickup device is composed of a circuit including a light receiving section such as a photodiode, and a reading section for reading electric signals based on the output of the light receiving section. Such a solid-state image pickup device is manufactured by stacking a plurality of layers on a semiconductor wafer by using a known technique.
By the way, in recent years, there has been a demand for high-density, high-resolution and small-size solid-state image pickup devices, and the pitch size per pixel shows a tendency to decrease. In order to satisfy such a demand, the area of the light receiving section (hereinafter referred to as the light receiving area) must be reduced. When the light receiving area is reduced, the amount of received light decreases and the dynamic range decreases, and therefore it is necessary to compensate for the decrease in the amount of received light by arranging micro-lenses on the light receiving section.
In general, on the surface of a semiconductor chip on which a functional element is formed as a solid-state image pickup device, micro-lenses are formed by processing a translucent resin into the form of on-chip lenses. Therefore, the micro-lenses cause unevenness in the surface of the solid-state image pickup device. The light receiving surface of the solid-state image pickup device is very important as a sensor, and if foreign matter adheres, the lightness and chromaticity change due to the foreign matter and the reproducibility of the captured image deteriorates, and there is also a possibility that the light receiving surface may be scratched. Thus, since the quality and reliability of the solid-state image pickup device deteriorate if foreign matter adheres, the light receiving surface of the solid-state image pickup device is protected by a translucent lid part made of glass, etc.
As described above, the solid-state image pickup device has a structure in which the light receiving surface is protected by the lid part. In particular, in a solid-state image pickup device having on-chip micro-lenses, the unevenness of the surface is extremely complicated. Therefore, after mounting the semiconductor chip in a package case made of ceramic, plastic, etc., the light receiving surface is covered with the lid part to protect the solid-state image pickup device in the package case and prevent entry of foreign matter from outside. However, since there is a limitation in decreasing the size of a solid-state image pickup device of the package structure, a structure shown in FIG. 1 is proposed. In this structure, a glass plate 106 is joined to the surface of a semiconductor chip 101 on which solid-state image pickup elements are formed through an epoxy-based resin sheet 104 having a perforated portion 103 formed only at the light receiving section 102 with an adhesive 105 (see, for example, Japanese Patent Application Laid-Open No. 2001-257334). Thus, by directly joining the glass plate 106 (lid part) to the semiconductor chip 101, it is possible to decrease the size of the solid-state image pickup device compared with the package structure.
However, in the above-described manufacturing method of solid-state image pickup device, the epoxy-based resin sheet 104 is used to ensure the spacing between the glass plate 106 and the semiconductor chip 101, and the glass plate 106 and the semiconductor chip 101 are adhered to both surfaces of the epoxy-based resin sheet 104 using the adhesive 105. Since the epoxy-based resin sheet 104 has a hole formed so that it is not positioned over the light receiving section 102, the tension applied to the sheet is uneven due to the influence of the hole. Consequently, the epoxy-based resin sheet 104 becomes very unstable in shape when attaching it, and there is a problem that the attaching step becomes extremely difficult. Moreover, when adhering the epoxy-based resin sheet 104 to the surface of the semiconductor chip 101, it takes a time for positioning the epoxy-based resin sheet 104 and the semiconductor chip 101, and there is also a problem that the management of the manufacturing steps is complicated because sufficient measures are not taken to prevent contamination of the light receiving surface on which the micro-lenses are arranged.
Further, in the epoxy-based resin sheet 104, since the perforated portion 103 is formed by producing a hole, there is a limitation in decreasing the size of the perforated portion 103. Since the size of the closed space of the solid-state image pickup device is determined by the perforated portion 103, there is a limitation in decreasing the size of the structure of the solid-state image pickup device even if the method disclosed in the Japanese Patent Application Laid-Open No. 2001-257334 is used.